Nerve growth factor: its significance in cutaneous biology.

Work in the past 10 y has greatly expanded our knowledge regarding the role of neurotrophins and, in particular, nerve growth factor, in skin. During fetal development, neurotrophins are expressed both in the mesenchyme and the epithelium of developing skin, and they play a trophic role supporting the survival of innervating neurons. Nerve growth factor appears to have an important role also in the adult organism. It serves as a regulatory molecule during skin inflammation and repair, affecting both the neuronal and the immune systems. Recent studies also suggest that nerve growth factor is an important autrocrine growth factor and survival factor for keratinocytes, cells that express both high- and low-affinity receptors for nerve growth factor. Neural crest-derived melanocytes also express receptors for nerve growth factor. Nerve growth factor appears to have a major role during skin injury, e.g., preventing melanocyte apoptotic cell death following UV irradiation. Thus, epidermal events interact to maintain the number and function of both melanocytes and keratinocytes in skin. These recent insights into the mechanisms underlying nerve growth factor effects in skin may eventually result in the development of novel therapeutic modalities.